From what I've learned, heard, seen, etc, the reason why hitting the chin knocks a person out is based on the the human head - brain's ability to absorb certain forces. They did a study on car crashes, and it showed that the human brain-head can take on direct blows well, ie a straight blow ( especially the forehead). But when the brain is forced to take on force that is more than a straight impact, like when its twisting force, the brain nerves - brain stem will "short circut" causing you to get knocked out. Thats why when you see someone get decked from a straight punch they get knocked down but not out. But a hook to the chin, which would provide the best leverage to move the head would cause the brain to twist a little. Also i believe the cutting off of the artiery to the brain is a common misconception, think about when you apply a triangle it takes a couple of seconds to pass him out not a split second

Immediately after biomechanical injury to the brain, abrupt, indiscriminant release of neurotransmitters and unchecked ionic fluxes occur. The binding of excitatory transmitters, such as glutamate, to the N-methyl-D-aspartate (NMDA) receptor leads to further neuronal depolarization with efflux of potassium and influx of calcium. These ionic shifts lead to acute and subacute changes in cellular physiology.

Acutely, in an effort to restore the neuronal membrane potential, the sodium-potassium (Na+-K+) pump works overtime. The Na+-K+ pump requires increasing amounts of adenosine triphosphate (ATP), triggering a dramatic jump in glucose metabolism. This “hypermetabolism” occurs in the setting of diminished cerebral blood flow, and the disparity between glucose supply and demand triggers a cellular energy crisis. The resulting energy crisis is a likely mechanism for postconcussive vulnerability, making the brain less able to respond adequately to a second injury and potentially leading to longer-lasting deficits.

Following the initial period of accelerated glucose utilization, the concussed brain goes into a period of depressed metabolism. Persistent increases in calcium may impair mitochondrial oxidative metabolism and worsen the energy crisis. Unchecked calcium accumulation can also directly activate pathways leading to cell death. Intra-axonal calcium flux has been shown to disrupt neurofilaments and microtubules, impairing posttraumatic neural connectivity.

This overview represents a simplified framework of the neurometabolic cascade (Figure 1). Other important components of posttraumatic cerebral pathophysiology include, but are not limited to, generation of lactic acid, decreased intracellular magnesium, free radical production, inflammatory responses, and altered neurotransmission. We will now discuss some of the pertinent details of postconcussive pathophysiology in both experimental animal models and in humans.

Essentially what it is saying, is that the brain is caught in a sudden cascade of chemical reactions. The body is constantly balancing potassium and sodium flux. ATP is the bodies energy source. Trying to check this large flux requires a lot of ATP. This depletes the brain's energy store and it's lights out.

While I agree with you in general, the woodpecker has evolved special adaptations that allows it to take an awful lot of impact to the head, and I don't see how this is an apt analogy with humans.

It's more about the same plane of motion than the force. As I already mentioned in my first post, a football or rugby player's head takes up to 4 times (!) the force of a knockout strike with every tackle. That's the same adaptation a woodpecker has, but to a much greater extent. You could probably still get a good whiplash effect and knockout by striking Woody's beak upward or sideways.

Omega's "bloxing with the face" isn't just a humorous troll comment.

Originally Posted by Marc Spector

Huh? Why not?

You'll only break your jaw that way. The pain could put you down for the count, but you won't have a concussion.

Calm down, it's only ones and zeros.

"Your calm and professional manner of response is really draining all the fun out of this. Can you reply more like Dr. Fagbot or something? Call me some names, mention some sand in my vagina or something of the sort. You can't expect me to come up with reasonable arguments man!" -- MaverickZ

It's more about the same plane of motion than the force. As I already mentioned in my first post, a football or rugby player's head takes up to 4 times (!) the force of a knockout strike with every tackle. That's the same adaptation a woodpecker has, but to a much greater extent.

Well, here's a theory that one of my friends told me. Like the article that you posted said, the helmets that the football players wear might have some effect. But my friend's theory said, that when you punch someone, you're focusing the attack in a smaller more specific area. While if you tackle someone, you're 'spreading' the attack all over the body. He said that possibly, if you focus your attack, it'll do more damage then a more 'spreaded out attack' because you're more focused on causing pain to that one specific area.

The point where the mandible articulated to the maxilla, if memory serves is one of the few points on the skull where two bones meet but don't fuse (think babies with the soft spots in the skull), however combined they are considered the 'srongest bones your face' (note I said face not skull). The occipital orbis and the zygomatic arch are bound to be broken if struck and are less dense, but won't necessarily cause you to be ko'ed as the bone will give way. Same way with the mandibular articulation will 'unhinge' at the maxilla and cause a dislocated jaw, but is able to accept the impact at a greater rate and thereby cause the potential shifting of the brain and in turn result in a potential contusion and ko.

My take on KO's for the last 24 years is much the same as that has already been covered, along the lines of what I term "brain shake", the chin being the best point of contact to maximise acceleration due to simple leverage, however the weakness in the chin as a target is that it is more difficult to get a good connection, as the natural subconscious "flinch" away from a punch to the face can be enough to make the attempted punch ineffective.

I tend to advise punching for the cheekbone, being on the centreline in relation to the appropriate shoulder that is being used, essentially aiming through the centre of mass/rotation of the head/neck, basically punching for the line of the spine.

This has the benefit of making it more difficult to get the head out of the way, also if the cheekbone is compressed it effects the sinuses and makes the eyes water, clouding vision and by focussing more on the brain stem as the target you are visualising through the head rather than targeting a surface feature.

As an aside I have only been knocked out once in my life, though I have been hit in the head on many occasions, once with piece of paving concrete, the particular situation is a bit of a long tale but suffice to say that I had my head on the road and had it stamped on repeatedly, so not much movement more simple compression, I had headaches for months after but obviously survived.

My point is that susceptibility to KO is a personal thing and cannot be predicted or relied upon and that you should always follow the Wing Chun adage (also streetfighting) of carry on hitting until the threat is no longer there.